Vertical shaft impact crushers (VSI-crushers) are used in many applications for crushing hard material like rocks, ore etc. U.S. Pat. No. 3,154,259 describes a VSI-crusher comprising a housing and a horizontal rotor located inside the housing. Material that is to be crushed is fed into the rotor via an opening in the top thereof. With the aid of centrifugal force the rotating rotor ejects the material against the wall of the housing. On impact with the wall the material is crushed to a desired size. The housing wall could be provided with anvils or have a bed of retained material against which the accelerated material is crushed.
The rotor of a VSI-crusher usually has a horizontal upper disc and a horizontal lower disc. The upper and lower discs are connected with a vertical rotor wall. The upper disc has an aperture for feeding material into the rotor. The material lands on the lower disc and is then thrown out of the rotor via openings in the rotor wall. The vertical rotor walls are provided with wear tips of a hard material, such as a hard metal or a ceramic, to protect them from wear caused by the material leaving the rotor at a high speed.
The wear tips described in U.S. Pat. No. 3,154,259 are fixed to holes in the upper and lower discs.
U.S. Pat. No. 3,174,697 describes impeller shoes for a rotor. The impeller shoes, which each have a hard metal tip, are bolted to a horizontal impeller disc.
GB 2,198,060 describes a carrier body. The carrier body, being a substantially plate shaped body, holds a hard metal tip at one end thereof. At a second end thereof the carrier body is bolted to the rotor wall by a through bolt. The bolt fixing the carrier body in position is subjected to heavy wear.
The wear tips described above are quite difficult to replace when they have become worn out. The down time related to maintenance work is thus rather long. In some cases a bolt wear protection plate is required to protect the bolt holding the wear tip.